Media streaming is growing in popularity and it constitutes a dominant portion of the total volume of wireless data consumed by mobile devices operating in a wireless communication network such as, for example, a cellular network. In media streaming, multimedia content such as audio-visual content, video segments, audio files, etc., is scrambled by the content provider prior to delivery and un-scrambled at the receiver to enforce legal restrictions associated with content streaming.
It is noted here that the terms “multimedia content,” “media”, “content,” or other terms of similar import are used interchangeably herein to primarily refer to data content having one or more of the following: audio components, video components (including animation, mobile gaming content, etc.), and image content, with or without accompanying textual information.
In the context of a wireless network, for example, a “provider” or “sender” of the multimedia content may include a Base Station (BS) or a Radio Base Station (RBS), a Base Station Controller (BSC), a Radio Network Controller (RNC), an evolved Node B (eNodeB or eNB), etc. On the other hand, a “receiver” of such content may include a mobile or wireless device operating in the wireless network such as, for example, a User Equipment (UE), a mobile handset, a cell phone, a tablet or laptop computer, etc.
The discussion below first addresses how information is handled in “streaming”, and then briefly discusses “downloading” as an alternative form of content delivery to better show the contrast between these two approaches.
Scrambling and Sandbox
In the discussion herein, the term “scrambled” is used to mean that data is modified in some way to make it unreadable, unless some additional information, in the form of a digital “key”, is available to “un-scramble” (also interchangeably referred to as “de-scramble” or “decrypt”) it. For example, the well-known public-key cryptography scheme uses a private/public key cryptography system where, at the transmitter, a scrambler uses a public key specific to the intended receiver. At the receiver, a de-scrambler uses a corresponding private key to retrieve the clear (i.e., unscrambled) data. Instead of this public-key cryptography scheme, a private-key cryptography scheme may be used, where the same private key is available at the transmitter as well as at the receiver.
An application is said to operate in a “sandbox” when other processes are not allowed to read the memory locations dedicated for that application. Also, the application operating in the sandbox may be forbidden from sharing its information in its dedicated memory with other applications in the same device, or transmitting that information with other devices. For example, a de-scrambler application may de-scramble information inside its “sandbox.” The de-scrambled or “clear” information/data may not be shared, for example, by writing it to memory locations outside the sandbox or by some other means. Such restrictions may be enforced by the operating system. This is essentially no different than how multiple virtual machines run on the same computer hardware, with separation between two virtual machines enforced by rules in the operating system.
Streaming
A streaming player in a receiver of streamed content reconstructs the current content from a small amount of recent information. Thus, the streaming player does not need to keep the older information. Although the streaming player does not have to erase the older information to function properly, it erases it because it is required to do so by the owner of the multimedia content or by the laws governing delivery and reproduction of streamed content.
Without much loss of generality, it is assumed here that streamed information is received at a client/receiver such as, for example, a mobile or wireless device, in a scrambled form. The streaming media player in the client may un-scramble the received information inside its sandbox, and process it to reconstruct the original content. As noted earlier, only the most current information is needed for this reconstruction. Hence, it is assumed that such current information is in the “clear” (i.e., de-scrambled) form only inside the sandbox. One way to erase the clear information as it gets old is to simply over-write it with new information. The clear information may be never seen outside the sandbox.
In normal live streaming, the client-based streaming media player renders the media for consumption at the client by processing information messages as they arrive. This requires a steady flow of messages in order to keep feeding the player with enough information. In a wireless network, the streaming bit rate may change within a relatively narrow range to adapt to varying channel conditions, and the reconstruction quality of the media may adapt accordingly. As noted below, due primarily to contractual/legal requirements, a streaming media player erases the received information as it is consumed; it only keeps the most recent information in memory.
The “streaming” differs from a “download” (discussed below) in that the streaming does not allow the entire content to be stored for repeated playback. If not explicit, there is an implied or implicit “contract” between a streaming server and its client restricting how the streamed content may be consumed. Some aspects of this streaming contract between the server/transmitter and the client/receiver are enforced by the structure of the streaming scheme itself. That is, the client does not receive messages beyond what it needs now. However, other aspects of the contract are enforced by the client itself. That is, de-scrambled information is in the clear only inside the client's sandbox and is erased as it gets consumed. It would be a violation of the streaming contract—and there would presumably be legal recourse if the violation is detected—if the client does not erase the information as required, or if the client shares clear information outside its sandbox. However, in the discussion herein, it is assumed that the content owner and its client are complying with their streaming contract and, hence, contract violation-related possibility will not be considered any further.
Media Download
In contrast to the streaming mode described earlier, media also may be transmitted as a “download.” In a download, the information needed to describe the complete content may be transferred as a data file. The whole file is then stored in a memory at the client. The client-based media player retrieves the information from the memory as needed and reconstructs the content.
The legal landscape governing media downloads is different from the above-described streaming contract-based legal landscape governing media streaming. In a media download, once the whole description of the content is in the client's memory, then, in principle, it can be played repeatedly, modified, distributed to other clients/systems, and so on. Thus, in a media download, there is significant loss of control on the part of the content owner. Consequently, the fees are typically much higher for downloading some content than for streaming it. On the other hand, some content is only available for streaming, and never for download. Streaming may be considered to be equivalent to a performance of the content, whereas a download may be considered to be ownership of it.
Modern wireless networks are moving in the direction of densification because cellular system deployment has reached practical limits in many urban areas, while data traffic only continues to increase. Hence, to increase area spectral efficiency to accommodate the increasing data traffic, network operators are moving in the direction of Heterogeneous Networks (HetNet). Heterogeneous networks are an attractive means of expanding mobile network capacity. A HetNet may support multiple radio access technologies, architectures, transmission solutions, and base stations of varying transmission power. Heterogeneous networks may consist of planned macro base station deployments that typically transmit at high power overlaid with several low power nodes such as pico base stations, distributed antennas, femto base stations, and relays. The low power nodes may be deployed to eliminate coverage holes such as, for example, “dead spots” or coverage holes in outdoor and indoor environments such as, for example, a geographical area having a large number of office buildings requiring heavy indoor data traffic, and also to increase the capacity/area of the network. Remote radio heads or distributed antennas may be connected to the macro base station using a high bandwidth, low-latency dedicated connection. These radio heads may have minimal autonomous intelligence and may act as extensions of the base station antenna ports. Fixed relays are infrastructure equipment that connect wirelessly to the network backbone. These relays aid in the signal transmission between the macro base station and the mobile users by receiving and re-transmitting the signals. Picocells and femtocells are small base stations that may be operating under the control of the macro base station and installed in dead spots or high traffic areas to increase the network coverage and capacity.
The low power nodes may provide radio coverage over “small cells,” which are cells within the larger macro cell. A small cell is a cell whose coverage area may be defined by the ability of terminals to communicate with it, such as, for example, the ability to listen to its control channel on the downlink, the ability to successfully attach to it, etc. The macro cell remains under the overall radio coverage of the macro base station. Thus, one or more small cells with large bandwidth may be available/overlaid within the coverage area of a macro cell with smaller bandwidth. The small cell coverage is assumed to be spotty, with users moving in and out of small cells while remaining connected the macro cell. Small cells offer the promise of very high data rate availability, due to the large bandwidth, proximity to the user, and the small number of users attached to a given small cell.